455
FXUS64 KBRO 191929
AFDBRO

Area Forecast Discussion
National Weather Service Brownsville TX
229 PM CDT Fri Jul 19 2024

...New SHORT TERM, LONG TERM, MARINE...

.SHORT TERM...
(Tonight through Saturday night)
Issued at 227 PM CDT Fri Jul 19 2024

The mid-level ridge across the Four Corners will gradually edge west
as the 500 mb trough over the Central U.S. and Southern Plains shows
slight height falls over Texas. A weak frontal boundary over South
Central Texas this afternoon has shown slow southward movement, but
should stall out before reaching portions deep South Texas and the
RGV.

The models keep a weak signal for a sea breeze in for Saturday
afternoon, and PWAT is sufficient though model chances remain on the
low end, around 15%. Any convection could contain brief heavy
rainfall, sudden gusty winds, and occasional lightning.

Temperatures should remain near to slightly above normal day and
night, with Saturday afternoon heat index values from 103 to 108
degrees. Rip current risk will remain low with light to moderate
winds on the Gulf.

&&

.LONG TERM...
(Sunday through next Friday)
Issued at 227 PM CDT Fri Jul 19 2024

Throughout much of the long term period, Deep South Texas will be
wedged between two high pressures: a mid to upper level high over
the western US and the Bermuda High in the western Atlantic. This
will leave our area within a slightly more unsettled pattern as
influences from a trough over the central and eastern CONUS results
in almost daily chances of showers and thunderstorms.

Sunday into Monday, a frontal boundary will dip southward into
central Texas as the trough mentioned above lowers heights to its
south and southwest. As convergence increases into south Texas,
isolated to scattered thunderstorms are possible for much of Deep
South Texas on Sunday and Monday. The Storm Prediction Center (SPC)
3 Day Outlook outlines a general outlook for thunderstorms for Deep
South Texas on Sunday. Overnight lows will range from the mid 70s to
lower 80s and high temperatures will reach into the mid to upper
90s, possibly hitting 100 over western Zapata and southern portions
of Starr Counties. However, increased cloud cover will limit heat
indices closer to 110, which may support Special Weather Statements
but not Heat Advisory criteria.

By Tuesday, the trough will continue to deepen, which will push the
mid level high to our west farther to the west. Chances of showers
and thunderstorms will continue Tuesday into Thursday. As elevated
precipitable water (PWAT) values increase over the region, heavier
rainfall will be possible and the Weather Prediction Center (WPC)`s
5 Day Excessive Rainfall Outlook includes our area within a Marginal
risk (>5%) for flash flooding on Tuesday. The Probability of
Precipitation (POP) increases from 40% to 50% on Tuesday to 60% to
70% on Wednesday. Following, Thursday into Friday, POPs lower as a
trough arrives over the Pacific Northwest and moves the mid level
high over the western US farther east and suppresses convection over
Deep South Texas. High temperatures will remain in the lower to mid
90s. Increased cloud coverage will keep heat indices beneath heat-
related advisories and statements.

&&

.AVIATION...
(18Z TAFS)
Issued at 1126 AM CDT Fri Jul 19 2024

Conditions are VFR with few to scattered low clouds across the
lower RGV and light winds. Not seeing evidence on satellite of
any sea breeze activity just yet, but there is a bit of
convergence near the coast. Surface high pressure is in control.
The HRRR shows a few pop up showers along the coast or just
inland in a few hours, later this afternoon. Model guidance
supports clear skies tonight and continuing light southeast
winds. A few hours of patchy fog may develop toward dawn
Saturday, with few to scattered low clouds through the morning.
VFR conditions primarily expected.

&&

.MARINE...
Issued at 227 PM CDT Fri Jul 19 2024

Now through Saturday night...High pressure will persist across the
north Gulf of Mexico maintaining mainly light, southeast to south
winds and low seas. Isolated showers and thunderstorms may develop
over the Gulf waters tonight.

Sunday through Friday...Gentle to moderate south-southeasterly
breezes are expected for the upcoming week as well as low to
moderate seas. Isolated to scattered showers and thunderstorms are
possible daily with the highest chances on Sunday as well as Tuesday
through Thursday.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             80  95  79  94 /   0  20  10  30
HARLINGEN               76  95  76  94 /   0  20   0  30
MCALLEN                 80  99  79  97 /  10  20   0  20
RIO GRANDE CITY         77  99  78  97 /  10  10   0  10
SOUTH PADRE ISLAND      82  89  82  89 /   0  10  10  30
BAYVIEW/PORT ISABEL     78  92  78  92 /   0  20  10  30

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&

$$

SHORT TERM...54-BHM
LONG TERM....65-Irish/68-AM
AVIATION...54-BHM